The present application relates to semiconductor structures, and particularly to semiconductor structures including electronic and photonic components on a common substrate and methods of manufacturing the same.
Integration of electronic (e.g., transistors, capacitors, resistors) and photonic (e.g., modulators, lasers, photodetectors, waveguides) components on a single integrated chip using a standard semiconductor process has been actively pursued to provide fast optical communication links. Complementary metal-oxide-semiconductor (CMOS) transistors are normally used in the electronic/photonic integrated circuit to drive the photonic components. CMOS transistors are also widely used in receiver circuits. It is well known that bipolar junction transistors (BJTs) have better analog and radiofrequency (RF) characteristics than CMOS transistors. Therefore, it is more desirable to employ BJTs in RF integrated circuits for high-frequency applications. The BJTs may also be combined with CMOS transistors in bipolar complementary metal oxide semiconductor (BiCMOS) integrated circuits to take advantage of the positive characteristics of both transistor types in the construction of the electronic/photonic integrated circuit. However, conventional BJT fabrication processes are not compatible with prevalent CMOS technologies and therefore incur much higher cost. In addition, the conventional BJT design requires larger layout area than CMOS transistors, further adding to the manufacturing cost. Therefore, methods to integrate CMOS technology compatible BJTs with various photonic components on a common substrate remain needed.